高强度柔性钻杆研制及试验

Development and Test of High-Strength Flexible Drill Rod

随着超短半径钻井水平距离逐步延伸,对其中重要工具柔性钻杆的力学与密封性能不断提出更高的强度要求。针对现阶段柔性钻杆结构强度要求高、寿命短、密封难的问题,研制了一种高强度柔性钻杆,采用球铰结构连接钻杆短节,使节与节既可以弯曲一定角度,又可以传递扭矩和钻压。利用有限元软件建立了该柔性钻杆单节三维有限元模型,采用应力分类法对柔性钻杆结构强度进行校核。开展了三节柔性钻杆的抗拉、抗压、抗扭结构强度以及承载后的密封性能的室内试验。试验结果表明:所研制的高强度柔性钻杆单独受载时,在承受31 kN·m极限扭矩,1 120 kN拉伸载荷,270 kN压缩载荷时仍能满足强度要求。所得结论可为油田高强度柔性钻杆的研制提供理论依据。

As the horizontal distance of ultrashort-radius drilling gradually extends,higher strength requirements are constantly being put forward for the mechanical and sealing performance of the flexible drill rod.In order to solve the existing problems of flexible drill rod such as high structural strength requirements,short service life and difficult sealing,a high-strength flexible drill rod was developed.A ball pivot structure was used to connect the pup joints of the drill rod,allowing the joints to bend at a certain angle while transmitting torque and WOB.The finite element software was used to build a 3D finite element model for single joint of the flexible drill rod,and the stress classification method was used to check the structural strength of the flexible drill rod.Finally,laboratory test was conducted on the tensile,compressive and torsional structural strength and load-bearing sealing performance of 3-section flexible drill rod.The test results show that when the developed high-strength flexible drill rod was loaded alone,it can still meet the strength requirements when subjected to an ultimate torque of 31 kN·m,a tensile load of 1120 kN and a compressive load of 270 kN.The conclusions provide a theoretical basis for the development of high-strength flexible drill rods in oilfields.